Studying biologically relevant interactions at the level of individual molecules is increasingly important in all fields of medical research. For example, characterizing precisely how antibodies interact with antigens provides insights into immune responses during vaccination or during autoimmune responses in systemic lupus erythematosus (SLE) and other diseases. Measuring the interactions of recombinant wild-type and mutant proteins that participate in coagulation and inflammation helps design small molecule inhibitors as drug candidates. Studying bacterial surface components that contribute to drug resistance leads to improved antibiotics or to new approaches to make bacteria less virulent. The objective of this proposal is to equip biomedical researchers in Oklahoma with a state-of-the-art instrument that measures the interaction of two label-free biomolecules using minute quantities of reagents. We request a Biacore T200 instrument that uses surface plasmon resonance (SPR) to measure, with high precision and sensitivity, biomolecular interactions in real time, yielding high quality affinity and kinetic data at temperatures from 4-45C. To optimize the instrument, we also request dedicated analysis software for epitope mapping, immunogenicity, concentration measurements, thermodynamics, and single cycle injections. The instrument will be vital for supporting numerous ongoing projects that have a major impact on human health and disease.